1. Field of the Invention:
This invention relates generally to fluid pressure measurement devices, and more particularly relates to devices measuring pressure within a fluid line of an IV administration set.
2. Description of Related Art:
In intravenous pressure monitoring systems, fluid pressures at the transducer coupling site can fall to a level below that of atmospheric pressure when the body is positioned lower than the transducer level. Due to a conventional design of the mechanical coupling between the fluid path and the transducer, contact between the fluid path and the transducer may be lost when fluid pressures at the transducer coupling site become negative, resulting in incorrect measurements by the transducer. Placement of the transducer below the level of the body may be impractical, and may also result in a pressure imbalance in the pressure monitoring systems. Manufacturers of physiological pressure systems therefore request that the transducer be level with the body cavity for which the measurement is to be made.
Intravenous delivery systems employing fluid sensors for monitoring the proper condition of the fluid conduit cannot always be accurately leveled with the patient. In order to enable the pressure monitoring system to carry a full range of monitoring functions, a coupling mechanism which does not lose contact with the transducer under negative pressure conditions is desirable. Conventional physiological pressure measurement systems employ coupling "domes" or fluid channels between the fluid path and the transducer. In a typical system, in order to insure adequate signal fidelity during declining pressures (as in the case of the diastolic phase of an arterial pressure, or a negative respiratory induced transient CVP pressure) a displaceable fluid such as water is interposed between the dome diaphragm and the transducer membrane surface. The diaphragm and the transducer membrane surface remain in communication due to the fact that water is an incompressible fluid, and a vacuum in the space between the diaphragm and transducer membrane surface would be created were they to separate.
It would be desirable to provide a coupling mechanism for a negative pressure measurement system which will not lose contact with the transducer under negative pressure conditions which is economical and effective to measure pressure in an IV line, under circumstances where the fluid pressure at the transducer would become negative due to a hydrostatic elevation gradient between the patient and the transducing device.